ScalaTest 1.0
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org/scalatest/FlatSpec.scala
]
trait
FlatSpec
extends
Suite with
ShouldVerb with
MustVerb with
CanVerbFlatSpec
, so if you prefer the word example you can use it. However, in this documentation
the word test will be used, for clarity and to be consistent with the rest of ScalaTest.)
Trait FlatSpec
is so named because
your specification text and tests line up flat against the left-side indentation level, with no nesting needed.
FlatSpec
's no-nesting approach contrasts with traits Spec
and WordSpec
, which use nesting
to reduce duplication of specification text. Although nesting does have the advantage of reducing text duplication,
figuring out the full specification text for one test can require back-tracking out of several levels of nesting, mentally prepending
each fragment of text encountered. Thus the tradeoff with the nesting approach of Spec
and WordSpec
is that
they have less duplicated text at the cost of being a bit challenging to read. Trait FlatSpec
offers the opposite
tradeoff. In a FlatSpec
text is duplicated more, but figuring out the full specification text for a particular test is
easier. Here's an example FlatSpec
:
import org.scalatest.FlatSpec import scala.collection.mutable.Stack class StackSpec extends FlatSpec { behavior of "A Stack" it should "pop values in last-in-first-out order" in { val stack = new Stack[Int] stack.push(1) stack.push(2) assert(stack.pop() === 2) assert(stack.pop() === 1) } it should "throw NoSuchElementException if an empty stack is popped" in { val emptyStack = new Stack[String] intercept[NoSuchElementException] { emptyStack.pop() } } }
Note: you can you must
or can
as well as should
in a FlatSpec
. For example, instead of
it should "pop
..., you could write it must "pop
... or it can "pop
....
Instead of using a behavior of
clause, you can alternatively use a shorthand syntax in which you replace
the first it
with the subject string, like this:
import org.scalatest.FlatSpec import scala.collection.mutable.Stack class StackSpec extends FlatSpec { "A Stack" should "pop values in last-in-first-out order" in { val stack = new Stack[Int] stack.push(1) stack.push(2) assert(stack.pop() === 2) assert(stack.pop() === 1) } it should "throw NoSuchElementException if an empty stack is popped" in { val emptyStack = new Stack[String] intercept[NoSuchElementException] { emptyStack.pop() } } }
Running either of the two previous three versions of StackSpec
in the Scala interpreter would yield:
A Stack - should pop values in last-in-first-out order - should throw NoSuchElementException if an empty stack is popped
In a FlatSpec
you write a one (or more) sentence specification for each bit of behavior you wish to
specify and test. Each specification sentence has a
"subject," which is sometimes called the system under test (or SUT). The
subject is the entity being specified and tested and also serves as the subject of the sentences you write for each test.
Often you will want to write multiple tests for the same subject. In a FlatSpec
, you name the subject once,
with a behavior of
clause or its shorthand, then write tests for that subject with it should
/must
can "do something"
phrases.
Each it
refers to the most recently declared subject. For example, the four tests shown in this snippet are all testing
a stack that contains one item:
behavior of "A Stack (with one item)" it should "be non-empty" in {} it should "return the top item on peek" in {} it should "not remove the top item on peek" in {} it should "remove the top item on pop" in {}
The same is true if the tests are written using the shorthand notation:
"A Stack (with one item)" should "be non-empty" in {} it should "return the top item on peek" in {} it should "not remove the top item on peek" in {} it should "remove the top item on pop" in {}
In a FlatSpec
, therefore, to figure out what "it
" means, you just scan vertically until you find the most
recent use of behavior of
or the shorthand notation.
A FlatSpec
's lifecycle has two phases: the registration phase and the
ready phase. It starts in registration phase and enters ready phase the first time
run
is called on it. It then remains in ready phase for the remainder of its lifetime.
Tests can only be registered while the FlatSpec
is
in its registration phase. Any attempt to register a test after the FlatSpec
has
entered its ready phase, i.e., after run
has been invoked on the FlatSpec
,
will be met with a thrown TestRegistrationClosedException
. The recommended style
of using FlatSpec
is to register tests during object construction as is done in all
the examples shown here. If you keep to the recommended style, you should never see a
TestRegistrationClosedException
.
Shared fixtures
A test fixture is objects or other artifacts (such as files, sockets, database
connections, etc.) used by tests to do their work. You can use fixtures in
FlatSpec
s with the same approaches suggested for Suite
in
its documentation. The same text that appears in the test fixture
section of Suite
's documentation is repeated here, with examples changed from
Suite
to FlatSpec
.
If a fixture is used by only one test, then the definitions of the fixture objects can
be local to the test function, such as the objects assigned to stack
and emptyStack
in the
previous StackSpec
examples. If multiple tests need to share an immutable fixture, one approach
is to assign them to instance variables. Here's a (very contrived) example, in which the object assigned
to shared
is used by multiple test functions:
import org.scalatest.FlatSpec class ArithmeticSpec extends FlatSpec { // Sharing immutable fixture objects via instance variables val shared = 5 "The Scala language" must "add correctly" in { val sum = 2 + 3 assert(sum === shared) } it must "subtract correctly" in { val diff = 7 - 2 assert(diff === shared) } }
In some cases, however, shared mutable fixture objects may be changed by tests such that
they need to be recreated or reinitialized before each test. Shared resources such
as files or database connections may also need to be created and initialized before, and
cleaned up after, each test. JUnit offers methods setUp
and
tearDown
for this purpose. In ScalaTest, you can use the BeforeAndAfterEach
trait,
which will be described later, to implement an approach similar to JUnit's setUp
and tearDown
, however, this approach often involves reassigning var
s
between tests. Before going that route, you should consider some approaches that
avoid var
s. One approach is to write one or more create-fixture methods
that return a new instance of a needed object (or a tuple or case class holding new instances of
multiple objects) each time it is called. You can then call a create-fixture method at the beginning of each
test that needs the fixture, storing the fixture object or objects in local variables. Here's an example:
import org.scalatest.FlatSpec import scala.collection.mutable.ListBuffer class MySuite extends FlatSpec { // create objects needed by tests and return as a tuple def createFixture = ( new StringBuilder("ScalaTest is "), new ListBuffer[String] ) "ScalaTest" can "be easy " in { val (builder, lbuf) = createFixture builder.append("easy!") assert(builder.toString === "ScalaTest is easy!") assert(lbuf.isEmpty) lbuf += "sweet" } it can "be fun" in { val (builder, lbuf) = createFixture builder.append("fun!") assert(builder.toString === "ScalaTest is fun!") assert(lbuf.isEmpty) } }
If different tests in the same FlatSpec
require different fixtures, you can create multiple create-fixture methods and
call the method (or methods) needed by each test at the begining of the test. If every test requires the same set of
mutable fixture objects, one other approach you can take is make them simply val
s and mix in trait
OneInstancePerTest
. If you mix in OneInstancePerTest
, each test
will be run in its own instance of the FlatSpec
, similar to the way JUnit tests are executed.
Although the create-fixture and OneInstancePerTest
approaches take care of setting up a fixture before each
test, they don't address the problem of cleaning up a fixture after the test completes. In this situation,
one option is to mix in the BeforeAndAfterEach
trait.
BeforeAndAfterEach
's beforeEach
method will be run before, and its afterEach
method after, each test (like JUnit's setUp
and tearDown
methods, respectively).
For example, you could create a temporary file before each test, and delete it afterwords, like this:
import org.scalatest.FlatSpec import org.scalatest.BeforeAndAfterEach import java.io.FileReader import java.io.FileWriter import java.io.File class MySuite extends FlatSpec with BeforeAndAfterEach { private val FileName = "TempFile.txt" private var reader: FileReader = _ // Set up the temp file needed by the test override def beforeEach() { val writer = new FileWriter(FileName) try { writer.write("Hello, test!") } finally { writer.close() } // Create the reader needed by the test reader = new FileReader(FileName) } // Close and delete the temp file override def afterEach() { reader.close() val file = new File(FileName) file.delete() } "A FileReader" should "read in the contents of a file correctly" in { var builder = new StringBuilder var c = reader.read() while (c != -1) { builder.append(c.toChar) c = reader.read() } assert(builder.toString === "Hello, test!") } it should "read in the first character of a file correctly" in { assert(reader.read() === 'H') } it should "work without a fixture" in { assert(1 + 1 === 2) } }
In this example, the instance variable reader
is a var
, so
it can be reinitialized between tests by the beforeEach
method.
Although the BeforeAndAfterEach
approach should be familiar to the users of most
test other frameworks, ScalaTest provides another alternative that also allows you to perform cleanup
after each test: overriding withFixture(NoArgTest)
.
To execute each test, Suite
's implementation of the runTest
method wraps an invocation
of the appropriate test method in a no-arg function. runTest
passes that test function to the withFixture(NoArgTest)
method, which is responsible for actually running the test by invoking the function. Suite
's
implementation of withFixture(NoArgTest)
simply invokes the function, like this:
// Default implementation protected def withFixture(test: NoArgTest) { test() }
The withFixture(NoArgTest)
method exists so that you can override it and set a fixture up before, and clean it up after, each test.
Thus, the previous temp file example could also be implemented without mixing in BeforeAndAfterEach
, like this:
import org.scalatest.FlatSpec import org.scalatest.BeforeAndAfterEach import java.io.FileReader import java.io.FileWriter import java.io.File class MySuite extends FlatSpec { private var reader: FileReader = _ override def withFixture(test: NoArgTest) { val FileName = "TempFile.txt" // Set up the temp file needed by the test val writer = new FileWriter(FileName) try { writer.write("Hello, test!") } finally { writer.close() } // Create the reader needed by the test reader = new FileReader(FileName) try { test() // Invoke the test function } finally { // Close and delete the temp file reader.close() val file = new File(FileName) file.delete() } } "A FileReader" should "read in the contents of a file correctly" in { var builder = new StringBuilder var c = reader.read() while (c != -1) { builder.append(c.toChar) c = reader.read() } assert(builder.toString === "Hello, test!") } it should "read in the first character of a file correctly" in { assert(reader.read() === 'H') } it should "work without a fixture" in { assert(1 + 1 === 2) } }
If you prefer to keep your test classes immutable, one final variation is to use the
FixtureFlatSpec
trait from the
org.scalatest.fixture
package. Tests in an org.scalatest.fixture.FixtureFlatSpec
can have a fixture
object passed in as a parameter. You must indicate the type of the fixture object
by defining the Fixture
type member and define a withFixture
method that takes a one-arg test function.
(A FixtureFlatSpec
has two overloaded withFixture
methods, therefore, one that takes a OneArgTest
and the other, inherited from Suite
, that takes a NoArgTest
.)
Inside the withFixture(OneArgTest)
method, you create the fixture, pass it into the test function, then perform any
necessary cleanup after the test function returns. Instead of invoking each test directly, a FixtureFlatSpec
will
pass a function that invokes the code of a test to withFixture(OneArgTest)
. Your withFixture(OneArgTest)
method, therefore,
is responsible for actually running the code of the test by invoking the test function.
For example, you could pass the temp file reader fixture to each test that needs it
by overriding the withFixture(OneArgTest)
method of a FixtureFlatSpec
, like this:
import org.scalatest.fixture.FixtureFlatSpec import java.io.FileReader import java.io.FileWriter import java.io.File class MySuite extends FixtureFlatSpec { type FixtureParam = FileReader def withFixture(test: OneArgTest) { val FileName = "TempFile.txt" // Set up the temp file needed by the test val writer = new FileWriter(FileName) try { writer.write("Hello, test!") } finally { writer.close() } // Create the reader needed by the test val reader = new FileReader(FileName) try { // Run the test using the temp file test(reader) } finally { // Close and delete the temp file reader.close() val file = new File(FileName) file.delete() } } "A FileReader" should "read in the contents of a file correctly" in { reader => var builder = new StringBuilder var c = reader.read() while (c != -1) { builder.append(c.toChar) c = reader.read() } assert(builder.toString === "Hello, test!") } it should "read in the first character of a file correctly" in { reader => assert(reader.read() === 'H') } it should "work without a fixture" in { () => assert(1 + 1 === 2) } }
It is worth noting that the only difference in the test code between the mutable
BeforeAndAfterEach
approach shown here and the immutable FixtureFlatSpec
approach shown previously is that two of the FixtureFlatSpec
's test functions take a FileReader
as
a parameter via the "reader =>
" at the beginning of the function. Otherwise the test code is identical.
One benefit of the explicit parameter is that, as demonstrated
by the "it should work without a fixture
" test, a FixtureFlatSpec
test need not take the fixture. So you can have some tests that take a fixture, and others that don't.
In this case, the FixtureFlatSpec
provides documentation indicating which
tests use the fixture and which don't, whereas the BeforeAndAfterEach
approach does not.
(If you have want to combine tests that take different fixture types in the same FlatSpec
, you can
use MultipleFixtureFlatSpec.)
If you want to execute code before and after all tests (and nested suites) in a suite, such
as you could do with @BeforeClass
and @AfterClass
annotations in JUnit 4, you can use the beforeAll
and afterAll
methods of BeforeAndAfterAll
. See the documentation for BeforeAndAfterAll
for
an example.
Sometimes you may want to run the same test code on different fixture objects. In other words, you may want to write tests that are "shared"
by different fixture objects. To accomplish this in a FlatSpec
, you first place shared tests in behavior functions.
These behavior functions will be invoked during the construction phase of any FlatSpec
that uses them, so that the tests they
contain will be registered as tests in that FlatSpec
. For example, given this stack class:
import scala.collection.mutable.ListBuffer class Stack[T] { val MAX = 10 private var buf = new ListBuffer[T] def push(o: T) { if (!full) o +: buf else throw new IllegalStateException("can't push onto a full stack") } def pop(): T = { if (!empty) buf.remove(0) else throw new IllegalStateException("can't pop an empty stack") } def peek: T = { if (!empty) buf(0) else throw new IllegalStateException("can't pop an empty stack") } def full: Boolean = buf.size == MAX def empty: Boolean = buf.size == 0 def size = buf.size override def toString = buf.mkString("Stack(", ", ", ")") }
You may want to test the Stack
class in different states: empty, full, with one item, with one item less than capacity,
etc. You may find you have several tests that make sense any time the stack is non-empty. Thus you'd ideally want to run
those same tests for three stack fixture objects: a full stack, a stack with a one item, and a stack with one item less than
capacity. With shared tests, you can factor these tests out into a behavior function, into which you pass the
stack fixture to use when running the tests. So in your FlatSpec
for stack, you'd invoke the
behavior function three times, passing in each of the three stack fixtures so that the shared tests are run for all three fixtures. You
can define a behavior function that encapsulates these shared tests inside the FlatSpec
that uses them. If they are shared
between different FlatSpec
s, however, you could also define them in a separate trait that is mixed into each FlatSpec
that uses them.
For example, here the nonEmptyStack
behavior function (in this case, a behavior method) is
defined in a trait along with another method containing shared tests for non-full stacks:
trait StackBehaviors { this: FlatSpec => def nonEmptyStack(stack: Stack[Int], lastItemAdded: Int) { it should "be non-empty" in { assert(!stack.empty) } it should "return the top item on peek" in { assert(stack.peek === lastItemAdded) } it should "not remove the top item on peek" in { val size = stack.size assert(stack.peek === lastItemAdded) assert(stack.size === size) } it should "remove the top item on pop" in { val size = stack.size assert(stack.pop === lastItemAdded) assert(stack.size === size - 1) } } def nonFullStack(stack: Stack[Int]) { it should "not be full" in { assert(!stack.full) } it should "add to the top on push" in { val size = stack.size stack.push(7) assert(stack.size === size + 1) assert(stack.peek === 7) } } }
Given these behavior functions, you could invoke them directly, but FlatSpec
offers a DSL for the purpose,
which looks like this:
it should behave like nonEmptyStack(stackWithOneItem, lastValuePushed) it should behave like nonFullStack(stackWithOneItem)
If you prefer to use an imperative style to change fixtures, for example by mixing in BeforeAndAfterEach
and
reassigning a stack
var
in beforeEach
, you could write your behavior functions
in the context of that var
, which means you wouldn't need to pass in the stack fixture because it would be
in scope already inside the behavior function. In that case, your code would look like this:
it should behave like nonEmptyStack // assuming lastValuePushed is also in scope inside nonEmptyStack it should behave like nonFullStack
The recommended style, however, is the functional, pass-all-the-needed-values-in style. Here's an example:
class SharedTestExampleSpec extends FlatSpec with StackBehaviors { // Stack fixture creation methods def emptyStack = new Stack[Int] def fullStack = { val stack = new Stack[Int] for (i <- 0 until stack.MAX) stack.push(i) stack } def stackWithOneItem = { val stack = new Stack[Int] stack.push(9) stack } def stackWithOneItemLessThanCapacity = { val stack = new Stack[Int] for (i <- 1 to 9) stack.push(i) stack } val lastValuePushed = 9 "A Stack (when empty)" should "be empty" in { assert(emptyStack.empty) } it should "complain on peek" in { intercept[IllegalStateException] { emptyStack.peek } } it should "complain on pop" in { intercept[IllegalStateException] { emptyStack.pop } } "A Stack (with one item)" should behave like nonEmptyStack(stackWithOneItem, lastValuePushed) it should behave like nonFullStack(stackWithOneItem) "A Stack (with one item less than capacity)" should behave like nonEmptyStack(stackWithOneItemLessThanCapacity, lastValuePushed) it should behave like nonFullStack(stackWithOneItemLessThanCapacity) "A Stack (full)" should "be full" in { assert(fullStack.full) } it should behave like nonEmptyStack(fullStack, lastValuePushed) it should "complain on a push" in { intercept[IllegalStateException] { fullStack.push(10) } } }
If you load these classes into the Scala interpreter (with scalatest's JAR file on the class path), and execute it, you'll see:
scala> (new SharedTestExampleSpec).execute() A Stack (when empty) - should be empty - should complain on peek - should complain on pop A Stack (with one item) - should be non-empty - should return the top item on peek - should not remove the top item on peek - should remove the top item on pop - should not be full - should add to the top on push A Stack (with one item less than capacity) - should be non-empty - should return the top item on peek - should not remove the top item on peek - should remove the top item on pop - should not be full - should add to the top on push A Stack (full) - should be full - should be non-empty - should return the top item on peek - should not remove the top item on peek - should remove the top item on pop - should complain on a push
One thing to keep in mind when using shared tests is that in ScalaTest, each test in a suite must have a unique name.
If you register the same tests repeatedly in the same suite, one problem you may encounter is an exception at runtime
complaining that multiple tests are being registered with the same test name. A good way to solve this problem in a WordSpec
is to make sure
each invocation of a behavior function is in the context of a different set of when
, verb (should
,
must
, or can), and that
clauses,
which will prepend a string to each test name.
For example, the following code in a WordSpec
would register a test with the name "A Stack (when empty) should be empty"
:
behavior of "A Stack (when empty)" it should "be empty" in { assert(emptyStack.empty) } // ...
Or, using the shorthand notation:
"A Stack" when { "empty" should { "be empty" in { assert(emptyStack.empty) } } } // ...
If the "should be empty"
test was factored out into a behavior function, it could be called repeatedly so long
as each invocation of the behavior function is in the context of a different combination
of when
, verb, and that
clauses.
FlatSpec
's tests may be classified into groups by tagging them with string names.
As with any suite, when executing a FlatSpec
, groups of tests can
optionally be included and/or excluded. To tag a FlatSpec
's tests,
you pass objects that extend abstract class org.scalatest.Tag
to taggedAs
method
invoked on the string that describes the test you want to tag. Class Tag
takes one parameter,
a string name. If you have
created Java annotation interfaces for use as group names in direct subclasses of org.scalatest.Suite
,
then you will probably want to use group names on your FlatSpec
s that match. To do so, simply
pass the fully qualified names of the Java interfaces to the Tag
constructor. For example, if you've
defined Java annotation interfaces with fully qualified names, com.mycompany.groups.SlowTest
and com.mycompany.groups.DbTest
, then you could
create matching groups for Spec
s like this:
import org.scalatest.Tag object SlowTest extends Tag("com.mycompany.groups.SlowTest") object DbTest extends Tag("com.mycompany.groups.DbTest")
Given these definitions, you could place FlatSpec
tests into groups like this:
import org.scalatest.FlatSpec class MySuite extends FlatSpec { "The Scala language" must "add correctly" taggedAs(SlowTest) in { val sum = 1 + 1 assert(sum === 2) assert(sum + 2 === 4) } it must "subtract correctly" taggedAs(SlowTest, DbTest) in { val diff = 4 - 1 assert(diff === 3) assert(diff - 2 === 1) } }
This code marks both tests with the com.mycompany.groups.SlowTest
tag,
and test "The Scala language should subtract correctly"
with the com.mycompany.groups.DbTest
tag.
The primary run
method takes a Filter
, whose constructor takes an optional
Set[String]
s called tagsToInclude
and a Set[String]
called
tagsToExclude
. If tagsToInclude
is None
, all tests will be run
except those those belonging to tags listed in the
tagsToExclude
Set
. If tagsToInclude
is defined, only tests
belonging to tags mentioned in the tagsToInclude
set, and not mentioned in tagsToExclude
,
will be run.
FlatSpec
provides a method
ignore
that can be used instead of it
to register a test. For example, to temporarily
disable the test with the name "A Stack should throw NoSuchElementException if an empty stack is popped"
, just
change “it
” into “ignore
,” like this:
import org.scalatest.FlatSpec import scala.collection.mutable.Stack class StackSpec extends FlatSpec { "A Stack" should "pop values in last-in-first-out order" in { val stack = new Stack[Int] stack.push(1) stack.push(2) assert(stack.pop() === 2) assert(stack.pop() === 1) } ignore should "throw NoSuchElementException if an empty stack is popped" in { val emptyStack = new Stack[String] intercept[NoSuchElementException] { emptyStack.pop() } } }
If you run this version of StackSpec
with:
scala> (new StackSpec).execute()
It will run only the first test and report that the second test was ignored:
A Stack - should pop values in last-in-first-out order - should throw NoSuchElementException if an empty stack is popped !!! IGNORED !!!
When using shorthand notation, you won't have an it
to change into ignore
for
the first test of each new subject. To ignore such tests, you must instead change in
to ignore
.
For example, to temporarily disable the test with the name "A Stack should pop values in last-in-first-out order"
,
change “in
” into “ignore
” like this:
import org.scalatest.FlatSpec import scala.collection.mutable.Stack class StackSpec extends FlatSpec { "A Stack" should "pop values in last-in-first-out order" ignore { val stack = new Stack[Int] stack.push(1) stack.push(2) assert(stack.pop() === 2) assert(stack.pop() === 1) } it should "throw NoSuchElementException if an empty stack is popped" in { val emptyStack = new Stack[String] intercept[NoSuchElementException] { emptyStack.pop() } } }
If you run this version of StackSpec
with:
scala> (new StackSpec).execute()
It will run only the second test and report that the first test was ignored:
A Stack - should pop values in last-in-first-out order !!! IGNORED !!! - should throw NoSuchElementException if an empty stack is popped
Informers
One of the parameters to the primary run
method is a Reporter
, which
will collect and report information about the running suite of tests.
Information about suites and tests that were run, whether tests succeeded or failed,
and tests that were ignored will be passed to the Reporter
as the suite runs.
Most often the reporting done by default by FlatSpec
's methods will be sufficient, but
occasionally you may wish to provide custom information to the Reporter
from a test.
For this purpose, an Informer
that will forward information to the current Reporter
is provided via the info
parameterless method.
You can pass the extra information to the Informer
via its apply
method.
The Informer
will then pass the information to the Reporter
via an InfoProvided
event.
Here's an example:
import org.scalatest.FlatSpec class ArithmeticSpec extends FlatSpec { "The Scala language" must "add correctly" in { val sum = 2 + 3 assert(sum === 5) info("addition seems to work") } it must "subtract correctly" in { val diff = 7 - 2 assert(diff === 5) } }
If you run this FlatSpec
from the interpreter, you will see the following message
included in the printed report:
scala> (new ArithmeticSpec).execute() The Scala language - must add correctly + addition seems to work - must subtract correctly
One use case for the Informer
is to pass more information about a specification to the reporter. For example,
the GivenWhenThen
trait provides methods that use the implicit info
provided by FlatSpec
to pass such information to the reporter. Here's an example:
import org.scalatest.FlatSpec import org.scalatest.GivenWhenThen class ArithmeticSpec extends FlatSpec with GivenWhenThen { "The Scala language" must "add correctly" in { given("two integers") val x = 2 val y = 3 when("they are added") val sum = x + y then("the result is the sum of the two numbers") assert(sum === 5) } it must "subtract correctly" in { given("two integers") val x = 7 val y = 2 when("one is subtracted from the other") val diff = x - y then("the result is the difference of the two numbers") assert(diff === 5) } }
scala> (new ArithmeticSpec).execute() The Scala language - must add correctly + Given two integers + When they are added + Then the result is the sum of the two numbers - must subtract correctly + Given two integers + When one is subtracted from the other + Then the result is the difference of the two numbers
A pending test is one that has been given a name but is not yet implemented. The purpose of pending tests is to facilitate a style of testing in which documentation of behavior is sketched out before tests are written to verify that behavior (and often, the before the behavior of the system being tested is itself implemented). Such sketches form a kind of specification of what tests and functionality to implement later.
To support this style of testing, a test can be given a name that specifies one
bit of behavior required by the system being tested. The test can also include some code that
sends more information about the behavior to the reporter when the tests run. At the end of the test,
it can call method pending
, which will cause it to complete abruptly with TestPendingException
.
Because tests in ScalaTest can be designated as pending with TestPendingException
, both the test name and any information
sent to the reporter when running the test can appear in the report of a test run. (In other words,
the code of a pending test is executed just like any other test.) However, because the test completes abruptly
with TestPendingException
, the test will be reported as pending, to indicate
the actual test, and possibly the functionality it is intended to test, has not yet been implemented.
You can mark tests as pending in FlatSpec
like this:
import org.scalatest.FlatSpec class ArithmeticSpec extends FlatSpec { // Sharing fixture objects via instance variables val shared = 5 "The Scala language" must "add correctly" in { val sum = 2 + 3 assert(sum === shared) } it must "subtract correctly" is (pending) }
If you run this version of ArithmeticSpec
with:
scala> (new ArithmeticSpec).execute()
It will run both tests but report that The Scala language must subtract correctly
is pending. You'll see:
The Scala language - must add correctly - must subtract correctly (pending)
One difference between an ignored test and a pending one is that an ignored test is intended to be used during a significant refactorings of the code under test, when tests break and you don't want to spend the time to fix all of them immediately. You can mark some of those broken tests as ignored temporarily, so that you can focus the red bar on just failing tests you actually want to fix immediately. Later you can go back and fix the ignored tests. In other words, by ignoring some failing tests temporarily, you can more easily notice failed tests that you actually want to fix. By contrast, a pending test is intended to be used before a test and/or the code under test is written. Pending indicates you've decided to write a test for a bit of behavior, but either you haven't written the test yet, or have only written part of it, or perhaps you've written the test but don't want to implement the behavior it tests until after you've implemented a different bit of behavior you realized you need first. Thus ignored tests are designed to facilitate refactoring of existing code whereas pending tests are designed to facilitate the creation of new code.
One other difference between ignored and pending tests is that ignored tests are implemented as a test tag that is
excluded by default. Thus an ignored test is never executed. By contrast, a pending test is implemented as a
test that throws TestPendingException
(which is what calling the pending
method does). Thus
the body of pending tests are executed up until they throw TestPendingException
. The reason for this difference
is that it enables your unfinished test to send InfoProvided
messages to the reporter before it completes
abruptly with TestPendingException
, as shown in the previous example on Informer
s
that used the GivenWhenThen
trait. For example, the following snippet in a FlatSpec
:
"The Scala language" must "add correctly" in { given("two integers") when("they are added") then("the result is the sum of the two numbers") pending } // ...
Would yield the following output when run in the interpreter:
The Scala language - must add correctly (pending) + Given two integers + When they are added + Then the result is the sum of the two numbers
Value Summary | |
protected val
|
behave
: BehaveWord
Supports shared test registration in
FlatSpec s. |
protected val
|
behavior
: BehaviorWord
Supports the registration of a “subject” being specified and tested.
|
protected val
|
ignore
: IgnoreWord
Supports registration of ignored tests in
FlatSpec s. |
protected val
|
it
: ItWord
Supports test (and shared test) registration in
FlatSpec s. |
protected implicit val
|
shorthandSharedTestRegistrationFunction
: (java.lang.String) => BehaveWord
Supports the shorthand form of shared test registration.
|
protected implicit val
|
shorthandTestRegistrationFunction
: (java.lang.String, java.lang.String, java.lang.String) => ResultOfStringPassedToVerb
Supports the shorthand form of test registration.
|
Method Summary | |
protected implicit def
|
convertToInAndIgnoreMethods
(resultOfStringPassedToVerb : ResultOfStringPassedToVerb) : InAndIgnoreMethods
Implicitly converts an object of type
ResultOfStringPassedToVerb to an
InAndIgnoreMethods , to enable in and ignore
methods to be invokable on that object. |
protected implicit def
|
convertToInAndIgnoreMethodsAfterTaggedAs
(resultOfTaggedAsInvocation : ResultOfTaggedAsInvocation) : InAndIgnoreMethodsAfterTaggedAs
Implicitly converts an object of type
ResultOfTaggedAsInvocation to an
InAndIgnoreMethodsAfterTaggedAs , to enable in and ignore
methods to be invokable on that object. |
protected implicit def
|
info
: Informer
Returns an
Informer that during test execution will forward strings (and other objects) passed to its
apply method to the current reporter. If invoked in a constructor, it
will register the passed string for forwarding later during test execution. If invoked while this
FlatSpec is being executed, such as from inside a test function, it will forward the information to
the current reporter immediately. If invoked at any other time, it will
throw an exception. This method can be called safely by any thread. |
override def
|
run
(testName : scala.Option[java.lang.String], reporter : Reporter, stopper : Stopper, filter : Filter, configMap : scala.collection.immutable.Map[java.lang.String, Any], distributor : scala.Option[Distributor], tracker : Tracker) : Unit
Runs this suite of tests.
|
protected override def
|
runTest
(testName : java.lang.String, reporter : Reporter, stopper : Stopper, configMap : scala.collection.immutable.Map[java.lang.String, Any], tracker : Tracker) : Unit
Run a test. This trait's implementation runs the test registered with the name specified by
testName . Each test's name is a concatenation of the text of all describers surrounding a test,
from outside in, and the test's spec text, with one space placed between each item. (See the documenation
for testNames for an example.) |
protected override def
|
runTests
(testName : scala.Option[java.lang.String], reporter : Reporter, stopper : Stopper, filter : Filter, configMap : scala.collection.immutable.Map[java.lang.String, Any], distributor : scala.Option[Distributor], tracker : Tracker) : Unit
Run zero to many of this
FlatSpec 's tests. |
override def
|
tags
: scala.collection.immutable.Map[java.lang.String, scala.collection.immutable.Set[java.lang.String]]
A
Map whose keys are String tag names to which tests in this Spec belong, and values
the Set of test names that belong to each tag. If this FlatSpec contains no tags, this method returns an empty Map . |
override def
|
testNames
: scala.collection.immutable.Set[java.lang.String]
An immutable
Set of test names. If this FlatSpec contains no tests, this method returns an
empty Set . |
Methods inherited from CanVerb | |
convertToStringCanWrapper |
Methods inherited from MustVerb | |
convertToStringMustWrapper |
Methods inherited from ShouldVerb | |
convertToStringShouldWrapper |
Methods inherited from Suite | |
nestedSuites, execute, execute, execute, execute, groups, withFixture, runNestedSuites, suiteName, pending, pendingUntilFixed, expectedTestCount |
Methods inherited from Assertions | |
assert, assert, assert, assert, convertToEqualizer, intercept, expect, expect, fail, fail, fail, fail |
Methods inherited from AnyRef | |
getClass, hashCode, equals, clone, toString, notify, notifyAll, wait, wait, wait, finalize, ==, !=, eq, ne, synchronized |
Methods inherited from Any | |
==, !=, isInstanceOf, asInstanceOf |
Class Summary | |
protected final class
|
BehaviorWord
extends AnyRef
Class that supports the registration of a “subject” being specified and tested via the
instance referenced from
FlatSpec 's behavior field. |
protected final class
|
IgnoreVerbString
(verb : java.lang.String, name : java.lang.String) extends AnyRef
Class that supports registration of ignored tests via the
IgnoreWord instance referenced
from FlatSpec 's ignore field. |
protected final class
|
IgnoreVerbStringTaggedAs
(verb : java.lang.String, name : java.lang.String, tags : scala.List[Tag]) extends AnyRef
Class that supports registration of ignored, tagged tests via the
IgnoreWord instance referenced
from FlatSpec 's ignore field. |
protected final class
|
IgnoreWord
extends AnyRef
Class that supports registration of ignored tests via the
ItWord instance
referenced from FlatSpec 's ignore field. |
protected final class
|
InAndIgnoreMethods
(resultOfStringPassedToVerb : ResultOfStringPassedToVerb) extends AnyRef
Class that supports test registration in shorthand form.
|
protected final class
|
InAndIgnoreMethodsAfterTaggedAs
(resultOfTaggedAsInvocation : ResultOfTaggedAsInvocation) extends AnyRef
Class that supports tagged test registration in shorthand form.
|
protected final class
|
ItVerbString
(verb : java.lang.String, name : java.lang.String) extends AnyRef
Class that supports test registration via the
ItWord instance referenced from FlatSpec 's it field. |
protected final class
|
ItVerbStringTaggedAs
(verb : java.lang.String, name : java.lang.String, tags : scala.List[Tag]) extends AnyRef
Class that supports the registration of tagged tests via the
ItWord instance
referenced from FlatSpec 's it field. |
protected final class
|
ItWord
extends AnyRef
Class that supports test (and shared test) registration via the instance referenced from
FlatSpec 's it field. |
Value Details |
protected
val
behavior : BehaviorWord
This field enables syntax such as the following subject registration:
behavior of "A Stack" ^
For more information and examples of the use of the behavior
field, see the main documentation
for this trait.
protected
val
it : ItWord
FlatSpec
s.
This field enables syntax such as the following test registration:
it should "pop values in last-in-first-out order" in { ... } ^
It also enables syntax such as the following shared test registration:
it should behave like nonEmptyStack(lastItemPushed) ^
For more information and examples of the use of the it
field, see the main documentation
for this trait.
protected
val
ignore : IgnoreWord
FlatSpec
s.
This field enables syntax such as the following registration of an ignored test:
ignore should "pop values in last-in-first-out order" in { ... } ^
For more information and examples of the use of the ignore
field, see the Ignored tests section
in the main documentation for this trait.
protected implicit
val
shorthandTestRegistrationFunction : (java.lang.String, java.lang.String, java.lang.String) => ResultOfStringPassedToVerb
For example, this method enables syntax such as the following:
"A Stack (when empty)" should "be empty" in { ... } ^
This function is passed as an implicit parameter to a should
method
provided in ShouldVerb
, a must
method
provided in MustVerb
, and a can
method
provided in CanVerb
. When invoked, this function registers the
subject description (the first parameter to the function) and returns a ResultOfStringPassedToVerb
initialized with the verb and rest parameters (the second and third parameters to
the function, respectively).
protected implicit
val
shorthandSharedTestRegistrationFunction : (java.lang.String) => BehaveWord
For example, this method enables syntax such as the following in:
"A Stack (with one item)" should behave like nonEmptyStack(stackWithOneItem, lastValuePushed) ^
This function is passed as an implicit parameter to a should
method
provided in ShouldVerb
, a must
method
provided in MustVerb
, and a can
method
provided in CanVerb
. When invoked, this function registers the
subject description (the parameter to the function) and returns a BehaveWord
.
protected
val
behave : BehaveWord
FlatSpec
s.
This field supports syntax such as the following:
it should behave like nonFullStack(stackWithOneItem) ^
For more information and examples of the use of behave
, see the Shared tests section
in the main documentation for this trait.
Method Details |
protected implicit
def
info : Informer
Informer
that during test execution will forward strings (and other objects) passed to its
apply
method to the current reporter. If invoked in a constructor, it
will register the passed string for forwarding later during test execution. If invoked while this
FlatSpec
is being executed, such as from inside a test function, it will forward the information to
the current reporter immediately. If invoked at any other time, it will
throw an exception. This method can be called safely by any thread.protected implicit
def
convertToInAndIgnoreMethods(resultOfStringPassedToVerb : ResultOfStringPassedToVerb) : InAndIgnoreMethods
ResultOfStringPassedToVerb
to an
InAndIgnoreMethods
, to enable in
and ignore
methods to be invokable on that object.protected implicit
def
convertToInAndIgnoreMethodsAfterTaggedAs(resultOfTaggedAsInvocation : ResultOfTaggedAsInvocation) : InAndIgnoreMethodsAfterTaggedAs
ResultOfTaggedAsInvocation
to an
InAndIgnoreMethodsAfterTaggedAs
, to enable in
and ignore
methods to be invokable on that object.override
def
tags : scala.collection.immutable.Map[java.lang.String, scala.collection.immutable.Set[java.lang.String]]
Map
whose keys are String
tag names to which tests in this Spec
belong, and values
the Set
of test names that belong to each tag. If this FlatSpec
contains no tags, this method returns an empty Map
.
This trait's implementation returns tags that were passed as strings contained in Tag
objects passed to
methods test
and ignore
.
protected override
def
runTest(testName : java.lang.String, reporter : Reporter, stopper : Stopper, configMap : scala.collection.immutable.Map[java.lang.String, Any], tracker : Tracker) : Unit
testName
. Each test's name is a concatenation of the text of all describers surrounding a test,
from outside in, and the test's spec text, with one space placed between each item. (See the documenation
for testNames
for an example.)testName -
the name of one test to execute.reporter -
the Reporter
to which results will be reportedstopper -
the Stopper
that will be consulted to determine whether to stop execution early.configMap -
a Map
of properties that can be used by this Spec
's executing tests.NullPointerException -
if any of testName
, reporter
, stopper
, or configMap
is null
.protected override
def
runTests(testName : scala.Option[java.lang.String], reporter : Reporter, stopper : Stopper, filter : Filter, configMap : scala.collection.immutable.Map[java.lang.String, Any], distributor : scala.Option[Distributor], tracker : Tracker) : Unit
FlatSpec
's tests.
This method takes a testName
parameter that optionally specifies a test to invoke.
If testName
is Some
, this trait's implementation of this method
invokes runTest
on this object, passing in:
testName
- the String
value of the testName
Option
passed
to this methodreporter
- the Reporter
passed to this method, or one that wraps and delegates to itstopper
- the Stopper
passed to this method, or one that wraps and delegates to itconfigMap
- the configMap
passed to this method, or one that wraps and delegates to it
This method takes a Set
of tag names that should be included (tagsToInclude
), and a Set
that should be excluded (tagsToExclude
), when deciding which of this Suite
's tests to execute.
If tagsToInclude
is empty, all tests will be executed
except those those belonging to tags listed in the tagsToExclude
Set
. If tagsToInclude
is non-empty, only tests
belonging to tags mentioned in tagsToInclude
, and not mentioned in tagsToExclude
will be executed. However, if testName
is Some
, tagsToInclude
and tagsToExclude
are essentially ignored.
Only if testName
is None
will tagsToInclude
and tagsToExclude
be consulted to
determine which of the tests named in the testNames
Set
should be run. For more information on trait tags, see the main documentation for this trait.
If testName
is None
, this trait's implementation of this method
invokes testNames
on this Suite
to get a Set
of names of tests to potentially execute.
(A testNames
value of None
essentially acts as a wildcard that means all tests in
this Suite
that are selected by tagsToInclude
and tagsToExclude
should be executed.)
For each test in the testName
Set
, in the order
they appear in the iterator obtained by invoking the elements
method on the Set
, this trait's implementation
of this method checks whether the test should be run based on the tagsToInclude
and tagsToExclude
Set
s.
If so, this implementation invokes runTest
, passing in:
testName
- the String
name of the test to run (which will be one of the names in the testNames
Set
)reporter
- the Reporter
passed to this method, or one that wraps and delegates to itstopper
- the Stopper
passed to this method, or one that wraps and delegates to itconfigMap
- the configMap
passed to this method, or one that wraps and delegates to ittestName -
an optional name of one test to execute. If None
, all relevant tests should be executed. I.e., None
acts like a wildcard that means execute all relevant tests in this Spec
.reporter -
the Reporter
to which results will be reportedstopper -
the Stopper
that will be consulted to determine whether to stop execution early.tagsToInclude -
a Set
of String
tag names to include in the execution of this Spec
tagsToExclude -
a Set
of String
tag names to exclude in the execution of this Spec
configMap -
a Map
of key-value pairs that can be used by this Spec
's executing tests.NullPointerException -
if any of testName
, reporter
, stopper
, tagsToInclude
, tagsToExclude
, or configMap
is null
.override
def
testNames : scala.collection.immutable.Set[java.lang.String]
Set
of test names. If this FlatSpec
contains no tests, this method returns an
empty Set
.
This trait's implementation of this method will return a set that contains the names of all registered tests. The set's
iterator will return those names in the order in which the tests were registered. Each test's name is composed
of the concatenation of the text of each surrounding describer, in order from outside in, and the text of the
example itself, with all components separated by a space. For example, consider this FlatSpec
:
import org.scalatest.FlatSpec class StackSpec extends FlatSpec { "A Stack (when not empty)" must "allow me to pop" in {} it must "not be empty" in {} "A Stack (when not full)" must "allow me to push" in {} it must "not be full" in {} }
Invoking testNames
on this Spec
will yield a set that contains the following
two test name strings:
"A Stack (when not empty) must allow me to pop" "A Stack (when not empty) must not be empty" "A Stack (when not full) must allow me to push" "A Stack (when not full) must not be full"
override
def
run(testName : scala.Option[java.lang.String], reporter : Reporter, stopper : Stopper, filter : Filter, configMap : scala.collection.immutable.Map[java.lang.String, Any], distributor : scala.Option[Distributor], tracker : Tracker) : Unit
If testName
is None
, this trait's implementation of this method
calls these two methods on this object in this order:
runNestedSuites(report, stopper, tagsToInclude, tagsToExclude, configMap, distributor)
runTests(testName, report, stopper, tagsToInclude, tagsToExclude, configMap)
If testName
is defined, then this trait's implementation of this method
calls runTests
, but does not call runNestedSuites
. This behavior
is part of the contract of this method. Subclasses that override run
must take
care not to call runNestedSuites
if testName
is defined. (The
OneInstancePerTest
trait depends on this behavior, for example.)
Subclasses and subtraits that override this run
method can implement them without
invoking either the runTests
or runNestedSuites
methods, which
are invoked by this trait's implementation of this method. It is recommended, but not required,
that subclasses and subtraits that override run
in a way that does not
invoke runNestedSuites
also override runNestedSuites
and make it
final. Similarly it is recommended, but not required,
that subclasses and subtraits that override run
in a way that does not
invoke runTests
also override runTests
(and runTest
,
which this trait's implementation of runTests
calls) and make it
final. The implementation of these final methods can either invoke the superclass implementation
of the method, or throw an UnsupportedOperationException
if appropriate. The
reason for this recommendation is that ScalaTest includes several traits that override
these methods to allow behavior to be mixed into a Suite
. For example, trait
BeforeAndAfterEach
overrides runTests
s. In a Suite
subclass that no longer invokes runTests
from run
, the
BeforeAndAfterEach
trait is not applicable. Mixing it in would have no effect.
By making runTests
final in such a Suite
subtrait, you make
the attempt to mix BeforeAndAfterEach
into a subclass of your subtrait
a compiler error. (It would fail to compile with a complaint that BeforeAndAfterEach
is trying to override runTests
, which is a final method in your trait.)
testName -
an optional name of one test to run. If None
, all relevant tests should be run. I.e., None
acts like a wildcard that means run all relevant tests in this Suite
.reporter -
the Reporter
to which results will be reportedstopper -
the Stopper
that will be consulted to determine whether to stop execution early.filter -
a Filter
with which to filter tests based on their tagsconfigMap -
a Map
of key-value pairs that can be used by the executing Suite
of tests.distributor -
an optional Distributor
, into which to put nested Suite
s to be run by another entity, such as concurrently by a pool of threads. If None
, nested Suite
s will be run sequentially.tracker -
a Tracker
tracking Ordinal
s being fired by the current thread.NullPointerException -
if any passed parameter is null
.IllegalArgumentException -
if testName
is defined, but no test with the specified test name exists in this Suite
ScalaTest 1.0
|
|